Here’s a story from my father. He was teaching a course for working professionals that had a large project component. He—being naive and idealistic—decided that as long as the students eventually finished the project, they had learned the material, so they should get full credit. Thus, his policy was that students could submit the project, get it graded, and then repeat this process as many times as they wanted. He knew this would mean extra work for him, but thought it would be worth it for the students.
The result, of course, was catastrophe.
To call the strategy many students took “abuse” gives no measure of their ingenuity. They realized that they could skip learning the material, and instead complete the project by running an evolutionary algorithm with my father’s grading as a reward function.
Edit: I will say though, I would give this grading scheme a poor grade too. The teacher recognizes it's more work for them, but doesn't seem to recognize it's also far more work for the students. Particularly those who care about their grades and are actually trying to abide by the spirit of the thing and not game the system.